The present invention discloses a high-strength prestressed composite ceramic and a preparation method thereof, and belongs to a ceramic reinforcing technology in the field of high-performance structural ceramics. Firstly, more than two kinds of bondable ceramics need to be determined to form a composite ceramic of a matrix material and a surface layer material, the matrix material should have sufficient strength and a higher expansion coefficient, and the surface layer material should have a lower expansion coefficient and a higher elastic modulus, realizing the balance of the surface layer compressive stress and the matrix tensile stress are formed after high-temperature co-sintering; and the surface layer compressive stress can greatly improve the bending strength of the composite ceramic. The magnitude of the compressive stress can be adjusted by optimizing the section ratio of the two materials of the cross sections, the surface prestress is designed to be more than the strength value of the surface layer material for the given two materials, and the section ratio is determined through deduction and calculation of a prestress calculation formula. The composite ceramic with prestress can be obtained after sintering greatly improving the strength. The present invention solves the current problem of difficulty in improving the strength of structural ceramics and has good practical value.

A method for increasing the room temperature ductility of an object made of a ceramic material is disclosed. The method includes providing an object made of a ceramic material, heating the object made of the ceramic material to a temperature to or above the brittle to ductile transition temperature of the ceramic material, introducing defects into the microstructure of the object by deforming the object at the temperature, and cooling the object to room temperature, resulting in room-temperature ductility higher than the room-temperature ductility of the object prior to the heating and deforming steps. A ceramic material subjected to the above-described method of achieving room-temperature ductility is also disclosed. An object made of ceramic material subjected to the above-described method of achieving room-temperature ductility is also disclosed.

A method of making a sintered ceramic body comprising the steps of disposing a ceramic powder (5) inside an inner volume of a spark plasma sintering tool (1), wherein the tool comprises: a die (2) comprising a sidewall comprising inner and outer walls, wherein the inner wall has a diameter defining the inner volume; upper and lower punches (4,4) operably coupled with the die, wherein each of the punches have an outer wall defining a diameter less than the diameter of the die inner wall, thereby creating a gap (3) between the punches and the inner wall when at least one of the punches are moved within the inner volume, and the gap is from 10 m to 70 m wide; creating vacuum conditions inside the inner volume; moving at least one of the punches to apply pressure to the ceramic powder while heating, and sintering; and lowering the temperature of the sintered body.

A method for remediating fractures in a cement structure including heating the cement structure to a temperature at or above the melting temperature of the eutectic metal alloy particles to allow the particles to flow in liquid state into the fractures in the cement structure until the heat source is discontinued, allowing the particles to cool and solidify.

A method of making a sintered ceramic body comprising the steps of disposing a ceramic powder inside an inner volume of a spark plasma sintering tool, wherein the tool comprises: a die comprising a sidewall comprising inner and outer walls, wherein the inner wall has a diameter defining the inner volume; upper and lower punches operably coupled with the die, wherein each of the punches have an outer wall defining a diameter less than the diameter of the die inner wall, thereby creating a gap between the punches and the inner wall when at least one of the punches are moved within the inner volume, and the gap is from 10 m to 70 m wide; creating vacuum conditions inside the inner volume; moving at least one of the punches to apply pressure to the ceramic powder while heating, and sintering; and lowering the temperature of the sintered body.

Inorganic ceramic coatings are disclosed whose chemical compositions comprise silicates, acids, metallic oxysalts such as tungstates and molybdates, water, and non-metallic oxides such as silicon oxide. The water-based inorganic ceramic coatings improve the ceramic, anti-corrosive and resistance properties of the metal substrates that are coated with same. A sol-gel process for synthesizing said the coatings comprises a process in which the non-metallic oxide, before being mixed with the rest of the components of the chemical compositions as claimed, can be pre-treated with hydrochloric acid and ammonium hydroxide, or can be sonicated to achieve a particle size in the range from approximately 160 to approximately 180 nm. A method for coating the metal parts with the inorganic ceramic coatings is also disclosed.

A method for remediating fractures in a cement structure including heating the cement structure to a temperature at or above the melting temperature of the eutectic metal alloy particles to allow the particles to flow in liquid state into the fractures in the cement structure until the heat source is discontinued, allowing the particles to cool and solidify.

A method of making a ceramic matrix composite (CMC) having an increased carbon content that may show improved resistance to chemical attack from molten silicon is described. The method includes depositing one or more matrix layers comprising boron nitride, silicon nitride, pyrolytic carbon, and/or silicon carbide on a fiber preform comprising one or more silicon carbide fibers. After depositing the matrix layer, the fiber preform is dipped into a coating solution comprising a polymer to deposit a polymeric layer on the matrix layer. After dip coating, the fiber preform is infiltrated with a slurry comprising ceramic particles and/or carbon particles to form a green body; after forming the green body, the polymeric layer is pyrolyzed to form a carbon-containing coating on the matrix layer; and the green body is then infiltrated with a melt comprising silicon or silicon alloy. Upon cooling the melt, a dense CMC formed may be obtained.

The present disclosure provides for methods of making a substrate having an antireflective coating, substrates having an antireflective coating, and the like. The present disclosure includes methods of increasing durability of the antireflective coating by heat-annealing a coated substrate such that nanoparticles in the coating reach a glass-transition temperature as well as substrates having an antireflective coating made using these methods.